1. Field of the Invention
The invention relates to electromagnetic pulse suppressor devices, and more particularly to extremely low inductance electromagnetic pulse suppressor devices.
2. Description of the Prior Art
Various kinds of power surges frequently occur in electrical conductors of electronic systems. Such power surges are frequently capable of destroying electronic components, rendering the electronic systems inoperative, and sometimes causing disasterous consequences. Various prior art devices for protecting electrical equipment against such transient power surges have been proposed. Semiconductor PN junction devices connected in circuitry to operate in the reverse breakdown or avalanche mode commonly have been packaged and connected in various configurations to suppress transient voltage surges which would otherwise destroy expensive electronic equipment. For example, see my U.S. Pat. No. 3,934,175 assigned to the present assignee.
Prior art surge suppression devices operate quite satisfactorily for certain types of power surges, especially those having relatively slow rise times. However, certain types of high voltage power surges or transient pulses, especially those caused by electrostatic discharges (ESD) and electromagnetic pulses, have extremely high speed rise times, of the order of kilovolts per nanosecond. Such high speed voltage voltage pulses can frequently cause destruction of a sensitive electronic circuit component, such as a MOS integrated circuit device, before the prior art surge depression devices can react to the extremely high speed transient pulses. The slow response of prior surge suppressors is mainly due inductance associated with their electrical lead connections. In the prior art surge suppressors, the electrical leads consist of a pair of lead conductors which extend from electrical lines conducting a power surge to the electrodes of the solid state avalanche mode PN junction devices which are the heart of the prior art surge suppressors. For more information on this topic, see the following references:
1. E. Van Keuren, Effects of EMP Induced Transients on Integrated Circuits, IEEE Electromagnetic Compatability Symposium Record, 75CH1002-5 EMC, 1975.
2. Owen J. McAteer, Shocking Blow to Military Electronics, Military Electronics/Countermeasures, June 1979.
3. T. J. Tucker, Spark Initiation Requirements of a Secondary Explosive, Annals of the New York Academy of Sciences, Volume 152, Article I, pp. 643-653, 1968.
4. O. Melville Clark, Suppression of Fast Rise-time Transients, Proceedings of 1st Symposium and Technical Exhibition on Electromagnetic Compatibility, IEEE 75CH1012-4 MONT, Montreux, Switzerland, 1975.
Accordingly, it is an object of the invention to provide a power surge protection device which is capable of effectively suppressing transient energy pulses or power surges having extremely high speed rise times.
It is another object of the invention to provide a power surge suppression device having extremely low inductance coupling between an electrical line conducting a power surge and a solid state PN junction suppressor chip.
Previously, when a large percentage of electronic devices is used consisted of "discrete" solid state components and "first generation" integrated circuit devices, average node capacitances of the circuitry were sufficiently high that the node capacitances could effectively suppress ordinary high voltage, high speed power surges, thereby preventing destruction of electronic components. However, in recent years tremendous reductions size of integrated circuits has occurred greatly reducing node capacitances. The great reductions in cost of electronic circuitry which have resulted from steadily increased miniaturization of integrated circuits has resulted in pervasive use of electronics throughout most segments of industry.
It is well known that the human body (which typically has a capacitance of 150 to 200 picofarads) frequently stores electrostatic charge which may be accumulated by walking on carpets, etc. Frequently, a person's body will be 30,000 to 40,000 volts different than the voltage of an object which the person touches. The resulting electrostatic discharge produces extremely fast rise time, high voltage transient voltages which are often coupled to electronic equipment. With the above mentioned pervasive use of electronic equipment, electrostatic discharge due to human bodies is causing increasing numbers of completely unanticipated electronic circuit failures, sometimes with disasterous consequences. Up to now, however, the electronics industry has not been able to provide a reliable, widely applicable protection system for protecting delicate electronic circuitry against such high speed, high voltage transients. Although large capacitances can sometimes be connected to power supply conductors to suppress such high speed, high voltage transients, frequently such capacitances are completely unacceptable.
Accordingly, it is another object of the invention to provide a power surge suppression device which economically and effectively suppress and dissipates voltage transients produced by electrostatic discharge from human bodies.